Technical Field
The present disclosure relates to the field of semiconductor technology, and more particularly to a silicon-on-insulator (SOI) substrate and a manufacturing method thereof.
Description of the Related Art
Transistors (e.g., MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors) formed using a silicon-on-insulator (SOI) substrate typically display improved performance compared to transistors formed on a bulk silicon substrate. For example, transistors formed using a SOI substrate are better suited for applications relating to RF (radio frequency) and high frequency modulation, power amplification/management, etc.
To meet the performance requirements for different applications, different types of transistors may be required. In particular, different transistors may require different types of source and drain regions, and also different semiconductor processes for forming the transistor well(s). To fabricate different transistors, different thicknesses of the buried oxide (BOX) layer and the topmost monocrystalline silicon layer in a SOI substrate may be required.
In a conventional SOI substrate, the topmost monocrystalline silicon layer (located above the BOX layer) generally has a uniform thickness over the entire substrate. However, as previously described, different thicknesses of the topmost monocrystalline silicon layer may be needed to fabricate transistors (having different device performance and structures) for different applications. As a result, it is difficult to fabricate different types of transistors on a single conventional SOI substrate. Thus, in the prior art, the different types of transistors are typically formed on different SOI substrates (each having a different monocrystalline silicon layer thickness), which increases the manufacturing costs and form factor of the semiconductor device.